Surgical instrument with safety mechanism

ABSTRACT

A surgical instrument including a handle assembly, a safety mechanism, an elongated body portion and a head portion is disclosed. The handle assembly includes a stationary handle, an approximation mechanism, and a firing trigger. A lever of the safety mechanism is movable between a first position where the firing trigger is prevented from being actuated, and a second position where the firing trigger is able to be actuated. A first jaw member of the head portion is movable in relation to a second jaw member of the head portion between spaced and approximated positions. Movement of the first jaw member in relation to the second jaw member from the approximated position towards the spaced position causes the lever of the safety mechanism to move from its second position to its first position.

This application claims priority to provisional application Ser. No.61/224,855, filed Jul. 11, 2009, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to a surgical instrument forapplying surgical staples to body tissue. More particularly, the presentdisclosure relates to a surgical stapling instrument suitable forperforming circular anastomosis and/or treatment to internal walls ofhollow tissue organs.

2. Background Of Related Art

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined. Depending on the desired anastomosisprocedure, the end sections may be joined by either circular,end-to-end, end-to-side, or side-to-side organ reconstruction methods.

In a circular anastomosis procedure, the two ends of the organ sectionsare joined by means of a stapling instrument which drives a circulararray of staples through the end section of each organ section andsimultaneously cores any tissue interior of the driven circular array ofstaples to free the tubular passage. Examples of instruments forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 7,303,106, 6,053,390, 5,588,579, 5,119,983, 5,005,749,4,646,745, 4,576,167, and 4,473,077, each of which is incorporatedherein in its entirety by reference. Typically, these instrumentsinclude an elongated shaft having a handle portion at a proximal end toactuate the instrument and a staple holding component disposed at adistal end. An anvil assembly including an anvil rod with attached anvilhead is mounted to the distal end of the instrument adjacent the stapleholding component. Opposed end portions of tissue of the hollow organ(s)to be stapled are clamped between the anvil head and the staple holdingcomponent. Typically, a first actuation mechanism is used to approximatethe anvil head and the staple holding component to clamp the tissue. Theclamped tissue is stapled by driving one or more staples from the stapleholding component so that the ends of the staples pass through thetissue and are deformed by the anvil head. Typically, a second actuationmechanism is used to fire the staples. It is also common for an annularknife to be concurrently advanced to core tissue within the hollow organto free a tubular passage within the organ.

Besides anastomosis of hollow organs, surgical stapling instruments forperforming circular anastomosis have been used to treat internalhemorrhoids in the rectum. Typically, during use of a circular staplinginstrument for hemorrhoid treatment, the anvil head and the stapleholding component of the surgical stapling instrument are insertedthrough the anus and into the rectum with the anvil head and the stapleholding component in an open or unapproximated position. Thereafter, apursestring suture is used to pull the internal hemorrhoidal tissuetowards the anvil rod. Next, the anvil head and the staple holdingcomponent are approximated to clamp the hemorrhoid tissue between theanvil head and the staple holding component. The stapling instrument isfired to remove the hemorrhoidal tissue and staple the cut tissue. Inother uses for hemorrhoid surgery, the stapling instrument is used toremove tissue just above the hemorrhoids in order to pull thehemorrhoids back up inside the rectum and reduce the symptoms. Thestaples interrupt the blood flow of the superior hemorrhoidal arterialbranches, cutting off the blood supply to the tissue, thus causing thehemorrhoids to shrink.

Some surgical stapling instruments include a safety device that preventsstaples from being fired before approximation of the anvil head and thestaple holding component.

SUMMARY

The present disclosure relates to a surgical instrument comprising ahandle assembly, a safety mechanism, an elongated body portion and ahead portion. The handle assembly includes a stationary handle, anapproximation mechanism, and a firing trigger. A lever of the safetymechanism is movable between a first position where the firing triggeris prevented from being actuated, and a second position where the firingtrigger is able to be actuated. An approximation mechanism moves thefirst jaw member in relation to the second jaw member from a spacedposition to an approximated position, wherein movement of the first jawmember in relation to the second jaw member from the approximatedposition towards the spaced position causes the lever to move from itssecond position to its first position.

In an embodiment, the lever is biased towards its first position. In apreferred embodiment, the safety mechanism includes a latch disposed onthe lever and a latch retainer disposed on the stationary handle,wherein the latch and latch retainer are configured to releasablymaintain the lever in its second position. The latch retainer can bebiased proximally.

In preferred embodiments, a predetermined amount of movement of thefirst jaw member from the approximated position towards its spacedposition causes distal movement of the latch retainer to release thelatch.

In some embodiments, the safety mechanism includes a plate disposed inmechanical cooperation with the stationary handle, and the plate isbiased distally. A lip of the plate preferably prevents movement of thelever towards its second position.

The lever is preferably configured to mechanically engage the firingtrigger when the lever is in its first position, the firing triggerfires a plurality of fasteners from the first jaw into contact with thesecond jaw.

The present disclosure provides in another aspect a surgical instrumentcomprising a handle assembly including a stationary handle, anapproximation mechanism, and a firing trigger for firing a plurality offasteners. A safety mechanism is disposed in mechanical cooperation withthe handle assembly and is movable between a first position to preventfiring of the fasteners and a second position to enable firing of thefasteners. The safety mechanism is retained in the second position. Anelongated body portion extends distally from the handle assembly. A headportion is disposed adjacent a distal end of the elongated body portionand includes a first jaw member and a second jaw member, the first jawmember being movable in relation to the second jaw member between spacedand approximated positions. An approximation mechanism moves the firstjaw member in relation to the second jaw member from a spaced positionto an approximated position, wherein movement of the first jaw member inrelation to the second jaw member from the approximated position towardsthe spaced position prior to firing of the fasteners causes the safetymechanism to be released to move from its second position to its firstposition.

In some embodiments, the plurality of fasteners are retained in thesecond jaw.

In preferred embodiments, the safety mechanism includes a lever retainedby a latch retainer in the second position. Preferably, a predeterminedamount of movement of the first jaw member from the approximatedposition towards the spaced position causes distal movement of the latchretainer to release the latch.

In some embodiments, the safety mechanism includes a plate disposed inmechanical cooperation with the stationary handle, the plate beingbiased distally and moved by the movement of the approximationmechanism. The lip of the plate in some embodiments prevents movement ofthe lever towards its second position.

DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical staplinginstrument are disclosed herein with reference to the drawings, wherein:

FIG. 1 is a perspective view of the presently disclosed surgicalstapling instrument illustrated in an unapproximated position, inaccordance with an embodiment of the present disclosure;

FIG. 2 is a perspective view of the surgical stapling instrument of FIG.1 illustrated in an approximated position;

FIG. 3 is a side view of the surgical stapling instrument of FIGS. 1 and2 illustrated in a fired position;

FIG. 4 is an longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the unapproximated position and a firstportion of a safety mechanism in a first position;

FIG. 5 is an longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the unapproximated position and a secondportion of the safety mechanism in a first position;

FIG. 6 is an longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the unapproximated position and thefirst portion and the second portion of the safety mechanism in thefirst position;

FIG. 7 is a longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the approximated position and the firstportion of the safety mechanism in a second position;

FIG. 8 is a longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the approximated position and the secondportion of the safety mechanism in a second position;

FIG. 9 is a longitudinal, cross-sectional view of a portion of thesurgical stapling instrument in the approximated position and the firstportion and the second portion of the safety mechanism in the secondposition;

FIG. 9A is an enlarged view of a portion of the surgical staplinginstrument of FIG. 9; and

FIG. 10 is a perspective view of a safety plate and latch retainer ofthe second portion of the safety mechanism as illustrated in FIGS. 5, 6,8, 9 and 9A.

DETAILED DESCRIPTION

Embodiments of the presently disclosed surgical stapling instrument willnow be described in detail with reference to the drawings in which likereference numerals designate identical or corresponding elements in eachof the several views.

Throughout this description, the term “proximal” will refer to theportion of the instrument closer to the operator and the term “distal”will refer to the portion of the instrument farther from the operator.

FIGS. 1-3 illustrate one embodiment of the presently disclosed surgicalstapling instrument and is generally referred to as reference number 10.Briefly, surgical stapling instrument 10 includes a handle assembly 12,an elongated body portion 14 including a curved elongated outer tube 14a, and a head portion 16. Alternately, in some surgical procedures,e.g., the treatment of hemorrhoids, it is desirable to have asubstantially straight body portion. It is contemplated herein that thelength, shape and/or the diameter of body portion 14 and head portion 16may also be varied to suit a particular surgical procedure.

With continued reference to FIGS. 1-3, handle assembly 12 includes astationary handle 18, a firing trigger 20, and a rotatable approximationmechanism 22. Head portion 16 includes a first jaw member (e.g., ananvil assembly 30) and a second jaw member (e.g., a shell assembly 31).Anvil assembly 30 is movable in relation to shell assembly 31 betweenspaced and approximated positions.

With continued reference to FIGS. 1-3, in operation, rotation ofapproximation mechanism 22 causes movement of anvil assembly 30 inrelation to shell assembly 31 between spaced (FIG. 1) and approximated(FIGS. 2 and 3) positions, as approximation mechanism 22 is mechanicallyengaged with anvil retainer 38 (FIG. 1), which is fastened to anvilassembly 30. It is envisioned that rotation of approximation mechanism22 in a first direction (e.g., clockwise) causes proximal movement ofanvil assembly 30 (i.e., towards its approximated position), androtation of approximation mechanism 22 in a second opposite direction(e.g., counter-clockwise) causes distal movement of anvil assembly 30(i.e., towards its spaced position). Details of the approximation aredisclosed for example in U.S. Pat. No. 7,303,106, the entire contents ofwhich are incorporated herein by reference.

Actuation of firing trigger 20 (i.e., pivoting in the direction of arrow“A” in FIG. 1), causes staples to be ejected from shell assembly 31towards anvil assembly 30. That is, firing trigger 20 is disposed inmechanical cooperation with a pusher (not explicitly shown in theillustrated embodiments), such that actuation of firing trigger 20causes advancement of the pusher into contact with the staples, whichejects the staples into staple deforming pockets of anvil assembly 30.Details of the firing are disclosed for example in U.S. Pat. No.7,303,106, the entire contents of which are incorporated herein byreference.

Referring now to FIGS. 4-9, approximation mechanism 22 is mechanicallyengaged with a screw stop 40 and screw stop 40 is in mechanicalcooperation with anvil assembly 30 (not shown). Here, rotation ofapproximation mechanism 22 in a first direction causes screw stop 40 tomove proximally, which in turn causes proximal movement of anvilassembly 30. As screw stop 40 moves proximally, a portion 42 thereof(see FIG. 9A) urges a portion (i.e., a plate 250) of safety mechanism200 proximally against the bias of a plate spring 260, as discussed inmore detail below. As a result, a lever 210 pivots in the direction ofarrow “C” in FIG. 6 to permit firing of surgical stapling instrument 10.That is, when lever 210 is in its first, blocking position (FIGS. 4-6),actuation of firing trigger 20 is prevented.

More particularly, and with continued reference to FIGS. 4-9, safetymechanism 200 (which is broken down into a first portion 200 a (FIGS. 4and 7) and a second portion 200 b (FIGS. 5 and 8), discussed in furtherdetail below, is disposed in mechanical cooperation with handle assembly12 and maintains firing trigger 20 in an open position (FIGS. 4-6) untilanvil assembly 30 and shell assembly 31 have been approximated. Safetymechanism 200 is also configured to prevent the actuation of firingtrigger 20 when anvil assembly 30 is moved relative to shell assembly 31from their approximated position towards their spaced position. That is,if the anvil assembly 30 and shell assembly 31 are in their approximatedposition (e.g., clamping tissue) and are then moved towards their spacedposition (e.g., unclamping tissue), safety mechanism 200 preventsactuation of firing trigger 20 until anvil assembly 30 and shellassembly 31 return to their approximated position. Thus, as can beappreciated, safety mechanism 200 helps prevent staples from being firedprematurely.

Various components of safety mechanism 200 are shown in FIGS. 4-9, withseveral components omitted in some figures for clarity. FIGS. 4-6illustrate safety mechanism 200 in its first, locking position. FIGS.7-9 illustrate safety mechanism 200 in its second, unlocked position.For ease of viewing clarity, as noted above, safety mechanism 200 hasbeen broken down into a first portion 200 a (shown individually in FIGS.4 and 7) and a second portion 200 b (shown individually in FIGS. 5 and8). Both first portion 200 a and second portion 200 b of safetymechanism 200 are shown in FIGS. 6 and 9.

With initial reference to FIGS. 4 and 7, first portion 200 a of safetymechanism 200 includes lever 210 having a latch 212, and a safety spring230. Lever 210 is pivotably disposed with respect to stationary handle18. Latch 212, which is shown integrally formed with lever 210, includesa tooth 214 having an angled surface 216 thereon. A distance “d” isdefined between tooth 214 and a surface 216 of lever 210 (see FIG. 4).

A distal portion 222 of safety spring 230 is configured to mechanicallyengage (e.g., pivotably engage) an aperture 218 of lever 210. A proximalportion 224 of safety spring 230 engages (e.g., is pinned to) a portionof stationary handle 18. Safety spring 230 is configured to bias lever210 in the substantial direction of arrow “B” in FIG. 4.

Second portion 200 b of safety mechanism 200 is illustrated in FIGS. 5and 8. Second portion 200 b includes plate 250 (an enlarged view ofwhich is shown in FIG. 10), plate spring 260, a latch retainer 270, anda retainer spring 280. Plate 250 is disposed within stationary handle 18and, as discussed above, plate 250 is configured for engagement by aportion of screw stop 40. More specifically, as screw stop 40 movesproximally, screw stop 40 contacts a distal portion 252 of plate 250(see FIGS. 9A and 10), thus creating a proximal force against plate 250.Plate spring 260, which is also disposed within stationary handle 18, isin mechanical cooperation with a proximal portion 254 of plate 250 andis configured to distally bias plate 250 against the proximal forceexerted thereon by screw stop 40. A rib 44 is disposed within stationaryhandle 18 and is configured and positioned to limit the distaltranslation of plate 250 (see FIGS. 5, 8 and 9A). More specifically, atleast one of tabs 253 (see FIG. 10) of plate 250 is configured to engagerib 44.

With continued reference to second portion 200 b of safety mechanism 200in FIGS. 5 and 8, latch retainer 270 and retainer spring 280 areillustrated. Latch retainer 270 is disposed in mechanical cooperationwith plate 250 and is slidably engaged therewith. Latch retainer hasseveral detents to engage the wall adjacent opening 258 in plate 250.Retainer spring 280 is disposed with stationary handle 18 and isconfigured to bias latch retainer 270 proximally with respect to plate250. It is envisioned that a distal portion 282 of retainer spring 280mechanically engages a portion 256 of plate 250 (see FIG. 10). Asdiscussed in detail below, the interaction between latch retainer 270,retainer spring 280 and plate 250 is configured to allow releasableengagement between latch 212 and latch retainer 270. A proximal portion284 of retainer spring 280 mechanically engages a portion of latchretainer 270.

In use, and with reference to FIGS. 6, 9 and 10, a distal lip 257 ofplate 250 contacts a blocking surface 220 of lever 210 (FIG. 5), thuspreventing rotation (i.e., in the substantial direction of arrow “C” inFIG. 6 of lever 210 until plate 250 is proximally moved a sufficientdistance such that distal lip 257 proximally passes blocking surface 220of lever 210. It is envisioned that rotation of approximation knob 22such that anvil assembly 30 and shell assembly. 31 are approximatedcauses screw stop 40 to proximally translate a sufficient distance sotab portion 42 causes distal lip 257 to proximally pass blocking surface220 (against the bias of plate spring 260). That is, once anvil assembly30 and shell assembly 31 are approximated (e.g., clamping tissuetherebetween), lever 210 is free to rotate (e.g., manually) from itsfirst blocking position (FIGS. 4-6) to its second enabling position(FIGS. 7-9) in the substantial direction of arrow “C” (against the biasof safety spring 230), thus enabling actuation of firing trigger 20.

With regard to FIG. 9A, an enlarged view of the interaction betweenlatch 212 and latch retainer 270 is shown. When lever 210 is rotatedfrom its first blocking position to its second enabling position, latch212 engages latch retainer 270. More particularly, angled surface 216 oflatch 212 is configured to make initial contact with latch retainer 270.The force exerted by rotation of lever 210 causes angled surface 216 oflatch 212 to distally translate latch retainer 270, with respect toplate 250, against the bias of retainer spring 280. After latch retainer270 is distally translated and tooth 214 of latch 212 passes a securingmember 272 of latch retainer 270, latch retainer 270 is translatedproximally via the bias of retainer spring 280, such that securingmember 272 is urged into the distance “d” between tooth 214 and surface216 of lever 210. In this position, latch 212 is releasably retained bylatch retainer 270, and actuation of firing trigger 20 is enabled.

If anvil assembly 30 and shell assembly 31 are moved towards theirspaced position (e.g., via rotation of approximation knob 22 in thesecond direction), thus possibly unclamping tissue, safety mechanism 200is configured such that lever 210 moves to its first, blocking position,thus preventing the firing of staples. In particular, as anvil assembly30 and shell assembly 31 are moved towards their spaced position, screwstop 40 is moved distally. Thus, the portion 42 of screw stop 40 thathad been in contact with and proximally urging distal portion 252 ofplate 250, also moves distally. Consequently, the distal bias of platespring 260 is not sufficiently resisted and plate 250 is distallytranslated. Upon distal translation of plate 250, latch retainer 270 andretainer spring 280 also translate distally (to a release point, asdiscussed below) such that latch retainer 270 releases latch 212. Therelease of latch 212, in combination with the bias asserted by safetyspring 230, causes lever 210 to move towards its first, blockingposition. Therefore, safety mechanism 200 prevents actuation of firingtrigger 30 after unclamping of tissue (i.e., anvil assembly 30 and shellassembly 31 are moved towards their spaced (=approximated) position.

As can be appreciated, the tolerances of various components of safetymechanism 200 help determine the amount of unclamping that is sufficientto return lever 210 to its first, blocking position. For example, therelease point may be dependent on an overlap “O” (FIG. 9A) between latch212 and securing member 272 of latch retainer 270. It is envisioned thatthe overlap “O” may be between about 0.010 inches and about 0.080inches, for example, depending on the desired effect. Other distancesare also contemplated. In such an example, the smaller the overlap “O,”the lower amount of unclamping that will be necessary to cause lever 210to return to its first, blocking position, and vice versa.

The present disclosure also contemplates the use of an indicatormechanism 100, as shown in FIGS. 4-9. In the first position, indicator102 provides indication to a surgeon that the instrument is in an open,non-approximated position. In the second position, indicator 102provides indication to a surgeon that the instrument has beenapproximated and is now in a fire-ready position. In the third position,indicator 102 provides indication to a surgeon that the instrument hasbeen fired. Further details of indicator mechanism are shown anddescribed in U.S. Pat. 7,303,106, incorporated hereinabove by reference.

The present disclosure also relates to a method of performing a surgicalprocedure. The method comprises the step of providing a surgicalinstrument, as described above, positioning the surgical instrumentadjacent a surgical site, and moving anvil assembly 30 with respect toshell assembly 31 from its approximated position towards its spacedposition to move the portion (e.g., lever 210) of safety mechanism 200from its second position to its first position.

Further details of other features of surgical instrument 10, such as theapproximation assembly, firing assembly, and lock out mechanism aredisclosed in commonly-owned U.S. Pat. Nos. 7,168,604 and 7,303,106, theentire contents of each of which are incorporated by reference herein.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, the disclosed safetymechanism may be used with other types of surgical instruments forjoining tissue, such as, for example, surgical stapling instrument withlinear jaw members, surgical instruments with curved jaw members andvessel sealing instruments. Further details of a linear surgicalstapling instrument are described in detail in commonly-owned U.S. Pat.No. 6,953,139 to Milliman et al., the entire contents of which arehereby incorporated by reference herein. An example of a commonly-ownedvessel sealing instrument is disclosed in U.S. Pat. No. 7,118,570, theentire contents of which are hereby incorporated by reference herein.Therefore, the above description should not be construed as limiting,but merely as exemplifications of disclosed embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

1-18. (canceled)
 19. A surgical instrument comprising: a handle assemblyincluding a firing mechanism; an elongated body portion extendingdistally from the handle assembly; a head portion disposed adjacent adistal end of the elongated body portion, the head portion including ananvil assembly and a shell assembly that are moveable between spaced andapproximated positions relative to one another, the shell assemblysupporting a plurality of staples, the firing mechanism being actuatableto eject the plurality of staples from the shell assembly; and a safetymechanism disposed in mechanical cooperation with the handle assembly,the safety mechanism including a lever moveable from a first positionpreventing actuation of the firing mechanism to a second positionpermitting actuation of the firing mechanism, the lever being biasedtowards the first position, the safety mechanism including a latchretainer for releasably retaining the lever in the second position,wherein the latch retainer releases the lever from the second positionin response to movement of the anvil and shell assemblies from theapproximated position towards the spaced position relative to oneanother.
 20. The surgical instrument of claim 19, wherein the leverincludes a latch configured to be releasably retained by the latchretainer to retain the lever in the second position.
 21. The surgicalinstrument of claim 19, wherein the safety mechanism includes a plateslidably disposed within the handle assembly, the plate defining anopening which receives a portion of the latch retainer therein.
 22. Thesurgical instrument of claim 21, wherein the latch retainer is biasedproximally relative to the plate.
 23. The surgical instrument of claim22, wherein the lever includes a latch disposed thereon, the latchretainer configured to engage the latch to retain the lever in thesecond position.
 24. The surgical instrument of claim 23, wherein thelatch moves the latch retainer distally as the lever is moved from thefirst position to the second position.
 25. The surgical instrument ofclaim 21, wherein the plate is biased distally relative to the handleassembly.
 26. The surgical instrument of claim 25, further comprising anapproximation mechanism for moving the anvil and shell assembliesbetween the spaced and approximated positions relative to one another,the approximation mechanism being engagable with the plate to move theplate proximally as the anvil and shell assemblies move relative to oneanother towards the approximated position.
 27. The surgical instrumentof claim 19, wherein the handle assembly includes a firing trigger, thelever being pivotal from the first position in engagement with thefiring trigger to the second position out of engagement with the firingtrigger.
 28. A surgical instrument comprising: a handle assemblyincluding a firing mechanism; an elongated body portion extendingdistally from the handle assembly; a head portion disposed adjacent adistal end of the elongated body portion, the head portion including ananvil assembly and a shell assembly, the head portion having a spacedposition in which the anvil assembly is spaced from the shell assemblyand an approximated position in which the anvil assembly is approximatedto the shell assembly, the shell assembly supporting a plurality ofstaples, the firing mechanism being actuatable to eject the plurality ofstaples from the shell assembly; and a safety mechanism disposed inmechanical cooperation with the handle assembly, the safety mechanismincluding a lever moveable from a first position preventing actuation ofthe firing mechanism to a second position permitting actuation of thefiring mechanism, the lever being biased towards the first position, thesafety mechanism including a latch retainer for releasably retaining thelever in the second position, wherein the latch retainer releases thelever from the second position in response to movement of the headportion towards the spaced position.
 29. The surgical instrument ofclaim 28, wherein the lever includes a latch configured to be releasablyretained by the latch retainer to retain the lever in the secondposition.
 30. The surgical instrument of claim 28, wherein the safetymechanism includes a plate slidably disposed within the handle assembly,the plate defining an opening which receives a portion of the latchretainer therein.
 31. The surgical instrument of claim 30, wherein thelatch retainer is biased proximally relative to the plate.
 32. Thesurgical instrument of claim 31, wherein the lever includes a latchdisposed thereon, the latch retainer configured to engage the latch toretain the lever in the second position.
 33. The surgical instrument ofclaim 32, wherein the latch moves the latch retainer distally as thelever is moved from the first position to the second position.
 34. Thesurgical instrument of claim 30, wherein the plate is biased distallyrelative to the handle assembly.
 35. The surgical instrument of claim34, further comprising an approximation mechanism for transitioning thehead portion between the spaced and approximated positions, theapproximation mechanism being engagable with the plate to move the plateproximally as the head portion moves towards the approximated position.36. The surgical instrument of claim 28, wherein the handle assemblyincludes a firing trigger, the lever being pivotal from the firstposition in engagement with the firing trigger to the second positionout of engagement with the firing trigger.